Many different elements must come together before a human community develops to the level of sophistication commonly referred to as civilization. The first is the existence of settlements classifiable as towns or cities. This requires food production to be efficient enough for a large minority of the community to be engaged in more specialized activities - such as the creation of imposing buildings or works of art, the practice of skilled warfare, and above all the administration of a centralized bureaucracy capable of running the machinery of state.

Civilization requires at least a rudimentary civil service.

In the organization of a civil service, a system of writing is an almost indispensable aid. This is not invariably the case because at least one civilization, that of the Incas in Peru, will thrive without writing. But the development of writing greatly enhances civilization. And with a script comes history.

Our knowledge of prehistory derives from surviving objects - the evidence of archaeology. History, by contrast, is based on documents. These various interconnections mean that history, civilization and writing all begin at the same time. That time is about 3100 BC.

Mesopotamia and Egypt: 3100 BC

In about 3200 BC the two earliest civilizations develop in the region where southwest Asia joins northeast Africa. Great rivers are a crucial part of the story. The Sumerians settle in what is now southern Iraq, between the mouths of the Euphrates and the Tigris. Egypt develops in the long narrow strip of the Nile valley.

Rivers offer two main advantages to a developing civilization. They provide water to irrigate the fields, and they offer the easiest method of transport for a society without paved roads. Rivers will play an equally important role in two other early civilizations - those of the Indus and of northern China.

The Indus: 2500 BC

It is not known whether contact with Mesopotamia inspires the first civilization of India or whether it is a spontaneous local development, but by about 2500 BC the neolithic villages along the banks of the Indus are on the verge of combining into a unified and sophisticated culture.

The Indus civilization, with its two large cities of Harappa and Mohenjo-daro, expands over a larger region than Egypt and Mesopotamia combined. It will survive, in a remarkably consistent form, for about 1000 years.

The Aegean: 2000 BC

The next region to develop a distinctive civilization centres on the Aegean Sea. The bays and inlets of the rugged coastal regions of Greece, and the many small islands strung like pearls across this relatively sheltered sea, combine to make this an ideal area for trade (and piracy) among people whose levels of nautical skill make short hops a necessary precaution.

The Aegean civilization stands at the start of the very lively tradition of Mediterranean culture. It begins in the large island which is perfectly placed to guard the entrance to the Aegean - Crete.

China: 1600 BC

The longest consistent civilization in the human story so far is that of China. This vast eastern empire seems set apart from the rest of the world, fiercely proud of its own traditions, resisting foreign influences. Its history begins in a characteristically independent manner.

There are no identifiable precedents for the civilization of the Shang dynasty, which emerges in China in about 1600 BC. Its superb bronze vessels seem to achieve an instant technological perfection. Its written texts introduce characters recognizably related to Chinese writing today. This is a civilization which begins as it will continue - with confidence.

America: 1200 BC

Around this time the earliest American civilizations have their beginnings, with the Olmecs in central America and the Chavin in the Andes.

Both these cultures develop large towns, centred on temples. Both are now famous for their sculpture. And each, in its own region, is at the start of a succession of civilizations leading directly to the two which are discovered and destroyed in the 16th century by the Spanish - the Aztecs in central America and the Incas in the Andes.

The Mediterranean: from 1000 BC

The first distinctively Mediterranean civilization, that of the Aegeans, comes to a sudden and still unexplained end in around 1200 BC. Some 200 years later an energetic seafaring people, the Phoenicians, become extensive traders. From their base in Lebanon they establish colonies along the coast of Africa and even into the Atlantic.

Their example, as Mediterranean imperialists, will be followed by the Greeks and then by the Romans. The Mediterranean becomes the world's most creative arena for the clash and synthesis of civilizations - a status which it has never entirely lost.

Regional civilizations: AD 400 - 1500

With the dominance of Greece and Rome in the west (both successfully managing a transition from pagan to Christian empires), of China in the east, and of strongly individual cultures in central and south America, each successive civilization in any region tends at this time to be a variation on local traditions. But sometimes there are upheavals which introduce an entirely new culture within already long-civilized parts of the world.

One such is Islam. The establishment of the caliphate in Damascus and then Baghdad leads to distinctively Muslim civilizations in an unbroken belt from north Africa to north India.

Global civilization: 16th - 20th century

The first sustained contact between Europe and America, in the 16th century, opens the door to a new concept - world-wide civilizations, evolving through colonies and empires. Spanish civilization is exported to Latin America. English culture spreads even further, in an empire which includes India, Australia, New Zealand, Canada and eventually many parts of Africa.

From the 16th to the 19th century it is this imperial impulse which carries European civilization round the world, often as a thin veneer over older and very robust local cultures. But by the 20th century there are different forces at work.

For much of the 20th century ideology has been the driving force in the export of two very different concepts of civilization, American capitalism and Russian Communism. At the same time mass communication has made it possible to export a region's popular culture to the rest of the world - notably that of America through radio, cinema and television.

Other influences, whether multinational companies or the internet, have a similar effect. The danger is of a worldwide sameness. But there is a corresponding benefit. Within economic limits, human communities are now free as never before to adopt the aspects of civilization which appeal to them - regardless of where they happen to be on the planet.